That article is somewhat wrong for macs since it is from 2007 so is a little outdated since starting in 10.6 and up mac will now have almost exactly the capacity they say. This is the actual link I should have posted but couldn't find it earlier http://support.apple.com/kb/TS2419.
Sorry this is getting this thread bait off topic now
So am I understanding this right: the mac has about a 4gb per 32gb error when reporting how much space is available? But it still has all of the space that apple claims? So really everything is there it just isn't recorded entirely? A 512gb sad drive still has 512gb but the computer just reports a bit less even though you can utilize all 512gb?